An Evaluation of Non-invasive ICP Monitoring in Patients Undergoing Invasive ICP Monitoring Via an External Ventricular Drainage (EVD) Device

Inclusion Criteria: * Adult men and women subjects, aged 18 years old and over at screening visit * Patients undergoing invasive ICP monitoring via an external ventricular drainage (EVD) device for clinical management * Survival expectancy greater than one week * Subject or legal authorized representative (per local regulation) is able and willing to comply with the requirements of the protocol * Subject or legal authorized representative (per local regulation) is able to understand and sign written informed consent to participate in the study Exclusion Criteria: * Subject with ear disease, ear trauma * Subjects with a bony abnormality (skull defect) * Subjects with severe head trauma in which the location and/or severity of the skull fracture(s), i.e. frank skull fracture or major joint dislocations may jeopardize HeadSense monitoring procedure * Subjects with cerebral fluid (CSF) leakage from the ear (CSF Otorrhea) * Known allergy or hypersensitivity to any of the test materials or contraindication to test materials * For women of childbearing potential: pregnancy (positive pregnancy test) or breast-feeding * Subjects currently enrolled in or less than 30 days post-participation in other investigational device or drug study(s), or receiving other investigational agent(s) * Any condition that may jeopardize study participation (e.g., abnormal clinical or laboratory finding) or interpretation of study results, or may impede the ability to obtain informed consent (e.g., mental condition)